Quantitative comparison of processes of oil- and water-based mud ...

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E72 Salazar and Torres-Verdín krw k0 rwS ew, n A-1 k rnw k 0 rnw 1 S n e nw , A-2 where k 0 rw and k 0 rnw are wetting- and nonwetting-phase relative permeability end points, respectively, and e w and e nw are empirical exponents for wetting and nonwetting phase, in that order. In equations A-1 andA-2, S n is normalized wetting-phase saturation, given by Sn Sw Swr , A-3 1 Swr Snwr where S w is saturation and S wr is irreducible saturation for the wetting phase, and S nwr is irreducible saturation for the nonwetting phase. Drainage capillary pressure is expressed as a function of porosity , permeability k Leverett, 1941, and wetting-phase water saturation, namely, P c P c 0 k 1 S n e p, A-4 where P c is capillary pressure between wetting and nonwetting phases, P c 0 is the coefficient for capillary pressure, and ep is the pore-size distribution empirical exponent. ACRONYMSAND NOMENCLATURE 1D One-dimensional AIT Array-induction imager tool BC Base case CMG Computer Modeling Group OBM Oil-based mud PVT Pressure-volume-temperature STARS Steam, thermal, and advanced processes reservoir simulator UT-FET The University of Texas-Formation Evaluation Toolbox WBM Water-based mud a Archie’s tortuosity factor, enw Empirical exponents for non-wetting-phase relative permeability, ep Pore-size distribution empirical exponent for capillary pressure, ew Empirical exponents for wetting-phase relative permeability, f s Mud solid fraction, h Reservoir thickness, m Mud-cake thickness, m k Formation permeability, md, m2 0 kmc Mud-cake permeability, md, m2 kmc Reference mud-cake permeability, md, m2 knw Nonwetting-phase permeability, md, m2 kri i-th-phase relative permeability, krnw Nonwetting-phase relative permeability, 0 krnw Nonwetting-phase-relative permeability end point, kw Wetting-phase permeability, md, m2 ACRONYMSAND NOMENCLATURE krw Wetting-phase relative permeability, krw0 Wetting-phase relative permeability end point, m Archie’s cementation exponent, N Number of radial gridblocks, n Archie’s saturation exponent, [NaCl] Equivalent salt concentration, ppm Pc Capillary pressure, Pa 0 Pc Coefficient for capillary pressure equation, Pa.cm Pm Mud hydrostatic pressure, Pa Pmc Mud-cake pressure, Pa Pnw Nonwetting phase pressure, Pa Pw Wetting phase pressure, Pa q Flow rate, m3 /d Flow rate of invasion, m3 /d qmf qmfave Average flow rate of invasion, m3 max qmf /d Maximum flow rate of invasion, m3 /d qmfstep Step flow rate of invasion, m3 /d r Radial distance from the center of the wellbore, m R10 10-inch radial length of investigation apparent resistivity, m R20 20-inch radial length of investigation apparent resistivity, m R30 30-inch radial length of investigation apparent resistivity, m R60 60-inch radial length of investigation apparent resistivity, m R90 90-inch radial length of investigation apparent resistivity, m rmc Mud-cake radius, m Rt True formation resistivity, m Rw Connate water resistivity, m rw Wellbore radius, m Sg Gas saturation, fraction Sn Normalized wetting phase saturation, fraction Snwr Nonwetting phase residual saturation, fraction So Oil saturation, fraction Sw Water saturation, fraction Swcr Critical water saturation, fraction Swin Initial water saturation, fraction Swr Wetting phase residual saturation, fraction T Temperature, °C t Time of invasion, hours, days Time of spurt loss, s tSL Vt Total volume of fluid injected, m3 Mud-cake exponent multiplier, Formation effective porosity, fraction Mud-cake porosity, fraction mc mc0 o mf Reference mud-cake porosity, fraction Oil viscosity, Pa.s Mud-filtrate viscosity, Pa.s Downloaded 29 Jul 2009 to 128.83.167.137. Redistribution subject to SEG license or copyright; see Terms of Use at http://segdl.org/
nw w ACRONYMSAND NOMENCLATURE Nonwetting phase viscosity, Pa.s Wetting phase viscosity, Pa.s Mud-cake compressibility exponent, REFERENCES Archie, G. E., 1942, The electrical resistivity log as an aid in determining some reservoir characteristics: Transactions of the American Institute of Mining, Metallurgical and Petroleum Engineers, 146, 54–62. Bigelow, E., 1992, Introduction to wireline log analysis: WesternAtlas International, Inc. Bourgoyne Jr., A. T., K. K. Millheim, M. E. Chenevert, and F. S. Young Jr., 1986, Applied drilling engineering: SPE Textbook Series. Brooks, R. H., and A. T. Corey, 1966, Properties of porous media affecting fluid flow: Journal of Irrigation and Drainage Division, 92, 61–88. Carlson, M. R., 2003, Practical reservoir simulation: PennWell. Chew, W. C., S. Barone, B. Anderson, and C. Hennessy, 1984, Diffraction of axisymmetric waves in a borehole by bed boundary discontinuities: Geophysics, 49, 1586–1595. Chin, W. 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Page 1 and 2: GEOPHYSICS, VOL. 74, NO. 1 JANUARY-
Page 3 and 4: Simulations are performed with comm
Page 5 and 6: Moreover, we use the Brooks-Corey e
Page 7 and 8: the flow rate of invasion reaches s
Page 9 and 10: equal to 0.1, 0.4, and 0.5 for wate
Page 11 and 12: Modeling of borehole resistivity me
Page 13 and 14: E F Figure 18. Radial distributions
Page 15: a) b) Figure 24. Two-foot vertical

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